Internal amide, nonpolymeric thioether sensitizers for photographic emulsions



United States Patent 3,165,552 INTERNAL ANHDENONPGLYll/ERIC THIGETHER SENSITIZERS FQR'PHOTQGRAPHIQ EMULSEQNS William G. Lovett, Peter P. Qhiesa, and John R. Darin,

Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Application Apr. 2, 1962, Ser. No. 184,496,

which is a division of application Ser. No. 858,872,

Dec. 11, 1959, now ?aten't No. 3,057,724, dated Get.

19, 1962. Divided and this application Apr. 6, 1964,

Ser. No. 357,801

6 Claims. (Cl. 269-561) This invention relates to photographic silver halide emulsions, and more particularly, to an improved means for sensitized such photographic silver halide emulsions.

This application is a division of our application Serial No. 184,496, filed April 2, 1962, which is, in turn, a

division of Serial No. 858,872, filed December 11, 1959, now US. Patent 3,057,724, issued October 19, 1962.

A number of methods have been previously described for increasing the sensitivity of photographic silver halide emulsions, other than methods of optical or spectral sensitization, which involve the incorporation of certain colored compounds or dyes in the emulsions. The incorporation of such dyes in the emulsions increases the optical range of sensitvity, and for this reason such dyes are commonly referred to as optical or spectral sensitizing dyes. It is also well known to increase the sensitivity of photographic emulsions by addition of sulfur compounds capable of reacting with silver salts to form silver sulfide, or with reducing agents (compounds of these types are also naturally present in gelatin), or with salts of gold or other noble metals, or with combinations of two or more of the aforementioned compounds generally known as chemical sensitizers. Such chemical sensitizers are believed to react with the silver halide to form, on the surface of the silver halide, minute amounts of silver sulfide or of silver or of other noble metals, and these processes are capable of increasing the sensitivity of developing-out emulsions by very'large factors. The process of chemical sensitization, however, reaches a definite limit beyond which further addition of sensitizer, or of further digestion with the sensitizer present, merely increases the fog of the photographic emulsion with constant or decreasing speed.

We have now found a means of further increasing the sensitivity of photographic emulsions which may be applied even though the ordinary processes of chemical sensitization have been carried to the effective limit of the photographic emulsion in question. Our process is to be distinguished from hypersensitization, which is produced by bathing a finished coating with water or with solutions of ammonia, amines or silver salts. Such processes act primarily on optically sensitized photographic emulsions and tend to increase the free silver'ion concentration of the emulsion and greatly diminish its stability. Our process is also to be distinguished from hypersensitization by mercury vapor, which gives a transitory effect which is lost on storage of the film. The compounds used in our invention do not appear to be chemical sensitizers in the usual sense, since they increase speed by their presence during exposure and processing and require no digestion With the photographic emulsion to produce an increase in speed, nor does their chemistry seem to indicate that they are likely to react with silver halide under normal emulsion conditions.

The novel sensitizers of our invention are quite unique in that the effects produced are additive in photographic emulsions which have already been sensitized to their optimum, or near optimum, with conventional chemical sensitizers, such as labile sulfur compounds. The novel sensitizers of our invention, however, can be used to sensitize photographic silver halide emulsions containing no other sensitizers, if desired. The novel sensitizers of our invention are not strictly chemical sensitizers, since chemical sensitizers do not generally provide the additive effects of the type mentioned.

It is, therefore, an object of our invention to provide photographic silver halide emulsions which have been sensitized with various non-polymeric compounds contain ng a plurality of sulfur atoms. Another object of our invention is to increase the sensitivity of ordinary photographic silver halide emulsions which have been sensitized with chemical sensitizers, such as compounds containing labile sulfur atoms, or gold-containing compounds. Other objects will become'apparent from a consideration of the following description and examples.

According to our invention, we have found that the sensitivity of an ordinary photographic silver halide emulsion can be materially increased by incorporating therein certain non-polymeric compounds which can, be characterized as thioethers containing internal amide linkages. By thioether, we mean a linkage wherein the sulfur atom is divalent and is joined to two non-oxocarbonylic carbon atoms. Compounds useful in sensitizing photographic silver halide emulsions according to the present invention are to be distinguished from the polymeric thioether compounds described in US. patent application Serial No. 779,874, filed December 12, 1958, now Patent No. 3,046,- 134, by J. R. Dann and I. J. Chechak. The polymeric compounds described in this latter application are generally characterized as having high molecular weight and as containing characteristic sulfur-containing repeating units or groups.

The sensitizing compounds useful in practicing our invention are non-polymeric and can be represented by the following general formula:

(Rz-SOHzCHlNHhR wherein R represents a methylene group, a substituted methylene group (e.g., methyl-substituted, ethyl-substituted, propyl-substituted, isopropyl-substituted, etc., methylene groups) or a p,p'-hexahydroxylylenyl group (i.e., a cyclohexylene-p,p'-bis methylene group), R represents a hydrogen atom or a methyl group and R represents an alkoxyalkyl group, such as methoxyethyl, ethoxyethyl, butoxyethyl, methoxypropyl, etc., an :alkoxyalkoxyalkyl group, such as ethoxyethoxyethyl, methoxyethoxyethyl, etc., a hydroxyalkyl group, such as fi-hydroxyethyl, 'y-hydroxypropyl, etc., a hydroxyalkoxyalkyl group, such as fl-hydroxyethoxyethyl, -hydroxypropoxyethyl, etc., a hydroxyalkoxyalkoxyalkyl group, such as B-hydroxyethoxyethoxyethyl, -hydroxypropoxypropoxyethyl, etc., or an aryloxyalkyl group, such as fl-phenoxyethyl, 'y-phenoxypropyl, etc.

Another group of useful sensitizing compounds embraced by our invention is that represented by the following general formula:

(niNNnr i omsomdHoNHnR wherein R and R eachlhave the values given above and R represents either two hydrogen atoms or a propen-lylidene-3 group. I

The compounds of Formulas I, H and III can be prepared according to methods illustrated below. Certain of these compounds can be prepared by the addition of a mercaptan compound across an olefinic double bond. Compounds containing a hydrazine group can be prepared by condensing hydrazine with the product resulting from the condensation of a carbethoxythiol compound across an olefinic double bond, while hydrazide compounds can be prepared by condensing the hydrazine compounds with an aldehyde, such as acrolein. These general methods can be illustrated as follows:

Method A.The addition of a mercaptan across an olefinic double bond, etc.

Basic Catalyst Method B.-The reaction of an alkyl halide with a thiolacetate compound in the presence of sumcient alkali to hydrolyze the thiolacetate to a mercaptan and, if desired, simultaneously effect its reaction with the alkyl halide. This allows the reaction to proceed without the isolation of the free mercaptan with its attendant difiiculties of purification and danger of oxidation to a disulfide, etc.

g g QNag G O 3 CH3 -SCH1OH3 NH CH2NHCCHZCH2sC CH3 Method C.-The reaction of hydrazine with compounds containing thioether groups and having ester end groups,

Method 'D.--The reaction of hydrazides of the type shown in Method C with aldehydes or ketones, e.g.

It is evident that the three above reactions (C and D) present a method of systematically increasing the ize and molecular weight of a molecule by definite integrals. To continue the above series, ethyl mercaptoacetate may be added across the new terminal double bonds and the reactions with hydrazine and then with acrolein will follow as shown above, each' series of three reactions will then add the group,

0 CH =ClH-CH=NNH-lI-OH -S to each end of the open chain compound.

on the steam bath under a reflux condenser.

Example 1 .7,9Diaza-1,15-Dihydroxy-3,1S-Dithiapentadecane-6,10-Dione Methylene bis acrylamide, 7,7 g. (0.05 mole), and 2-mercaptoethanol, 7.8 g. (0.10 mole) were dissolved in 50 ml. of absolute ethanol containing 10 drops of a 30% methanolic solution of benzyl trimethylammonium hydroxide. The reaction mixture was heated for 2 hours The product was filtered from the cooled reaction mixture and recrystallized from ethanol. M.P. 17l-l73 C.

Analysis-Called. for C H N S O C, 42.6; H, 7.1; S, 20.6; N, 9.0. Found: C, 42.5; H, 6.9; S, 20.6; N, 8.7.

Example 2 .1 0,12-Diaza-3,19-Di0xa-6,16-Dithiaheneic0sane-9,13-Dione Reaction of methylene bis acrylamide thiolacetate and ethoxyethyl bromide.

In 300 ml. ethanol were dissolved 4.4 g. of methylene bis acrylamide thiolacetate (0.0144 mole) (prepared as described in Example 1 from methylene bis acrylamide and thiolacetic acid) and 6.1 g. ethoxyethyl bromide (0.04 mole). To this were added 4.2 g. of sodium carbonate 0.04 mole) dissolved in 250 ml. of distilled Water. After refluxing 6 hours, the mixture was chilled and the white crystals formed were filtered and dried. The yield of product recrystallized from ethanol was 3.45 g. and the melting point was 166-l 67 C.

Analysis.Calcd. for C H N S O C, 49.1; H, 8.2; S, 17.5; N, 7.7; mol. wt., 366. Found: C, 49.4; H, 7.8; S, 17.4; N, 8.0; mol. wt., 326.

Example 3.13,15Diaza-3,6,22,25-Tetram-9,19-Dithiaheptac0sane-12,16-Dione Reaction of methylene bis acrylamide thiolacetate and ethoxyethoxyethyl bromide.

CH COSCH CH CONHCH NHCOCH CH SCOCH +2CH CH OCH CH OCH CH Br- CH CH OCH CH OCH CH SCH CH CONH) CH This compound was made by the same general method as Example 2. The melting point Was 129l31 C.

Analysis.-Calcd. for C1gH3 N 2S205: C, H, S, 14.1; N, 6.2; mol. wt., 454. Found: C, 50.2; H, 8.2; S, 14.3; N, 6.6; mol. wt., 471.

Example 4.--9,10-Diaza-2,I8-Dioxa-5,IS-Dithianonadecane-8,12-Di0ne Reaction of methylene bis acrylamide thiolacetate and methoxyethyl bromide.

This compound was made by the same general method as Example 2. The melting point was 129131 'C.

Anaylsis.Calcd. for C H N S O C, 46.1; H, 7.7; S, 18.9; N, 8.3; mol. wt., 338. Found: C, 46.2; H, 7.7; S,19.2; N, 8.6;11101. Wt., 332.

Example 5 Preparation of the dihydrazide of 6,8-diaza-1,13-dicarboxy-2,12-dithiatridecane-5,9-dione.

ZNH NH (021160 i l-(311234311203? d-NH 0H,

The reaction product obtained by adding 0.2 mole of ethylmercaptoacetate to 0.1 mole of methylene bis acrylamide was heated in 75 ml. of 65% hydrazine hydrate for one hour on the steam bath under a reflux condenser. After standing for 2 days at room temperature, white crystals were formed. These were washed with water and recrystallized from ethanol to give a product melting at 19920l C.

Analysis.-Calcd. for C H S N O C, 36.1; H, 6.0; N, 22.9; S, 17.5. Found: C, 36.0; H, 5.9; N, 22.9; S, 17.3.

Example 6 Preparation of 4,5,12,14,21,22-hexaza-8,18-dithia-1,3, 22,24-pentacosatetraene-6, 1 1,15 ,20tetrone.

O (CH CHOH=NNHyJ CH SCH CH ll-NH) 2on1 Acrolein, 0.23 g. (0.004 mole) and the dihydrazide of 6,8 diaza-l,13-dicarboxy-2,l2-dithiatridecane-5,9-dione, 0.72 g. (0.002 mole), were dissolved in 37 m1. of water and 12 ml. of ethanol. The reaction mixture was heated CCH CH C ONHCH, E CHZNHC O CHQCHZ Cl 2HSCH CH O CH3CH3 CHsOHgO omomsomonno ONHCHz@CH NHC o CHgCHgSCHgCHzO omen,

on the steam bath for 45 minutes and the white precipitate was filtered ofI and washed with ethanol. The melting point was 260 C. dec.

Analysis.Calcd. for C qH N S O C, 46.1; H, 5.9; N, 19.0; S, 14.5. Found: C, 46.5; H, 6.2; N, 19.4; S, 14.8.

Example 7. 8,1 0-1) ldZa-JJ 7-Dihydroxy-4,14-Dithiaheptadecane-7,11-Di0ne Reaction of methylene bis acrylamide thiolacetate and 3-bromo-1-propanol. r

0 l (110 CHgCHzOHzSCEgCHzNHMCE:

This compound was made by the same general method as Example 2. The melting point was 163-165 C.

Analysis.-Calcd. for C H S N O C, 46.2; H, 7.7; S, 18.9; N, 8.3. Found: C, 46.2; H, 7.8; S, 19.1; N, 8.6.

Example 8.1.0,12-Diaza-3,19-Di0xa-1,21-Diphen0xy- 6,1 6-Dithiaheneic0sane-9,13-Di0ne Reaction of methylene bis acrylamide thiolacetate and phenoxyethoxyethyl chloride.

This compound was made by the same general method as Example 2. M.P. 203-210" C.

(CHFOHC ONHhCHHCH; 2HSCH2CH2OCH2CH3 /OH (CH3CH2OCH2CE2SCH2CHZC ONH)gCHr-CH-CH \OH? This compound was made by the same general method as Example 1. M.P. 9799 C.v

Analysis.Calcd. for C H N S O C, 52.8; H, 8.8; N, 6.9; S, 15.7. Found: C, 53.0; H, 8.9; N, 7.0; S, 15.8. Example 11 .Bis-1,4-(Ethoxyethylmercaptoethylcarbonylamidomethyl) -Cyclohexane Reaction of bis-1,4-(chloroethylcarbonylamidomethyl) -cyclohexane and Z-mercaptoethoxyethane.

NagG O 3 alcohol This compound was made by refluxing the above ingredients for 7 hours, evaporating the solvents and extracting the desired product with hot absolute ethanol. Upon cooling, the precipitate obtained was filtered and recrystallized fromethanol. M.P. 157159 C.

AIZHIYSiSr-OEICCL IECtI' C22H43N2S2O4: C, 57.1; H, 9.1; N, 6.1; S, 13.8. Found: C, 56.9; H, 9.2; N, 5.7; S, 13.9.

Example 12 7 Preparation of his 1,4-(chloroethylcarbonylamidomethyl)-cyclohexane (intermediate for Example 11).

Nmomonmm zoiomomoooi o1oH,on,ooNn:oH,@omNrrooomomol 14.2 g. (0.1 mole) of bis 1,4-(aminomethyl)cyclohexane were run from a dropping funnel into 25.4 g. (0.2 mole) of fi-chloropropionyl chloride in 70 ml. dry ether with cooling and stirring over a period of 30 minutes. The mixture was held for 2 hours at room temperature and the resulting white pricipitate filtered off. The precipitate was recrystallized from 1300 ml. of ethanol. Four grams of the desired product, melting between 191-193" C. were obtained.

Analysis.Calcd. for C H O N CI C, 52.0; H, 7.4;

N, 5.1; S, 11.9. Found: C, 57.6; H, 6.8; N, 6.0; S, 12.1. N, 8.7; Cl, 22.0. Found: C, 52.0; H, 7.7; N, 8.7; Cl, 22.3.

7 Example 1 3 Preparation of isopropyl N,N'(methylene bis acrylamide).

| H01 onaonono 2orn=orrooNrn on orncnontNnoocn=onm One mole of acrylamide (71 g.) and 0.5 mole of isobutyraldehyde (36 g.) were dissolved in 'ZO ml. distilled water and 60 ml. concentrated hydrochloric acid. The mixture lwas warr'ned to 30-35 C. for 15 minutes, then cooled, the product filtered OE, and recrystallized from ethanol. The yield of material was 44 g. M.P. 270 C.

Analysis.-Calcd. for C1QH1602N2: C, 8.2; N, 14.3. FoundzC, 60.9; H, 8.1; N, 13.9.

The sensitizing compounds of our invention can be added to ordinary photographic silver halide emulsions for the purpose of increasing the sensitivity thereof, as has been indicated above.

The particular quantity of sensitizer used in a given emulsion can vary, depending upon the eifects desired, degree of ripening, silver content of the emulsion, etc. The amount used is also dependent upon the particular stage at which the sensitizer was added during the preparation of the emulsion. We have found that generally from about 50 mg. to about 5 g. of sensitizer per mole of silver halide are quite adequate to accomplish the desired sensitization. e e

The sensitizers of our invention can be added to photographic emulsions using any of the well known techniques in emulsion making. For example, the sensitizers can be dissolved in a suitable solvent and added to the silver halide emulsion, or they can be added to the emulsion in the form of a dispersion similar to the technique used toincorporate certain types of color-forming compounds (couplers) in a photographic emulsion. Techniques of this type are described in Jelley et al. US. Patent 2,322,027, issued June 15, 1943, and Fierke et al. U.S. Patent 2,801,171, issued July 30, 1957. As indicated above, the solvent should be selected so that it has no harmful efiect upon the emulsion, and generally solvents or diluents which are miscible with water are to be preferred. Water or dilute alkali is a dispersing medium for some of the sensitizers of the invention. In a preferred embodiment, the sensitizers can be dissolved in a solvent, such as ethanol, acetone, pyridine, N,N-dimethylformamide, etc'., and added to the emulsion in this form- If desired, certain of the sensitizers can be prepared in finely-divided form and dispersed in water alone, or in the presence of a suitable dispersing agent (such as alkali metal salts. of aromatic or aliphatic sulfonic acids) and range.

added to the emulsion in this form. It is quite apparent that the sensitizers of our invention should have sufiicient water-dispersibility so that they can be adsorbed to or associated with the grains of the silver halide present in the emulsion in suflicient amount to sensitize the emulsion. It is apparent that the optimum amount for each of the sensitizers will vary somewhat from emulsion to emulsion and from compound to compound. The optimum amount of any given sensitizer can be determined from any particular emulsion by running a series of tests in which the quantity of sensitizer is varied over a given Exposure of the treated emulsion in conventional photographic testing apparatus, such as an intensity scale sensitometer, will reveal the most advantageous concentrations for that sensitizer in that particular emulsion. Such matters are well understood by those skilled in the art.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be eflfected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims. v

What we claim as our invention and desire secured by Letters Patent of the United States is:

1. A compound of the formula:

wherein R represents a member selected from the class consisting of methylene, methyl-substituted methylene, ethyl-substituted methylene, n-propyl-substituted methylene, isopropyl-substituted methylene and cyclohexylenep,p'-bis methylene, R represents a member selected from the class consisting of hydrogen and methyl and R represents a member selected from the class consisting of methoxyethyl, ethoxyethyl, butoxyethyl, methoxypropyl, ethoxyethoxyethyl, methoxyethoxyethyl, fl-hydroxyethyl, 'y-hydroxypropyl, fl-hydroxyethoxyethyl, 'y-hydroxypropoxyethyl, ,B-hydroXyethoXyethoXyethyl, 'y-hydroxypropoxypropoxyethyl, fi-phenoxyethyl, -hydroxypropyl, hydrazinocarbonylmethyl and propen-l-ylidenehydrazinocarbonylmethyl.

2. 10,12-diaZo-3,19-dioXa-6,16-dithiaheneicosane 9,13- dione.

3. 13,15-diaza-3,6,22,25 tetroxa 9,19 dithiaheptacosane-12,16-dione.

4. 9,10-diaza-2,l8-dioXa-5,15 dithianonadecane 8,12- dione.

5. 8,10-diaza-1,l7-dihydroxy- 4,14 dithiaheptadecane- 7,11-dione.

6. 10,12-diaza-8,14-dimcthyl-3,19-dioXa 6,16 dithiaheneicosane-9,'13-dione.

No references cited. 

1. A COMPOUND OF THE FORMULA: 